Photographic element and process

ABSTRACT

Photographic elements incorporating anionic azo dyes and poly(styrene-maleimide) cationic mordants can be exposed and processed by dye bleach means to yield improved positive dye images. The scope of the present invention is defined by the following specification and claims.

O United States Patent [151 3,642,482 Williams, Jr. et al. 451 F b, 15, 1972 [54] PHOTOGRAPH: ELEMENT AND [56] Referem Cited PROCESS UNITED STATES PATENTS Inventors: Carl J. Williams, J PiltSfOfd; willilm 3,048,487 8/ 1962 Minsk ..96/84 KIIWIIBL'ROChE-SWI, both 3,075,841 1/ 1963 Lehman ..96/l14 [73] Assignce: Eastman Kodak Company, Rochester, FOREIGN PATENTS 0R APPLICATIONS .Y. 618,712 4/1961 Canada ..96/S7 Flled= Apr-21,1969 906,083 9/1962 Great Britain ..96/84 l 85 [2]] No 8 8,0 Primary Examiner-Norman G.Torchin R l d Us, A li ti D 7 Assistant Examiner-J. R. Hightower AttorneyW. H. J. Kline, J. R. Frederick and D. M. De Leo [63] Continuation-impart of Ser. No. 655,758, July 25,

1967, abandoned. 57 STR T Photographic elements incorporating anionic azo dyes and [52] U.S.C| ..96/53, 96/57,96/73 poly(styrene maleimide) cationic mordants can be exposed [51 1 Int. Cl ..G03c 7/00 and processed by dye bleach means to yield improved i i [58] Field of Search ..96/73, 114, 57, 84, 53 dye m The scope f the present invention is d fi d by the following specification and claims.

12 Claims, No Drawings PHOTOGRAPHIC ELEMENT AND PROCESS This invention relates to photography and in particular to novel photographic elements designed for use in dye bleach systems and to the dye bleach process associated therewith.

The selective destruction of azo dyes to obtain positive dye images is well known in the photographic art. Such operations are typically designated dye bleach processes which operate to reduce a colored dye to a colorless form in the presence of photographically developed silver.

The reductive dye bleaching is accomplished by one of two known processes, namely as a stoichiometric reaction in an acid solution, wherein the photographic silver functions as the reducing agent, or as a silver catalyzed reaction wherein the reducing agent is a highly alkaline substance such as sodium stannite (alkaline stannous chloride).

A typical multicolor silver dye bleach element is composed essentially of a support coated with silver halide layers differentially sensitized to blue, green, and red radiation and has in association therewith, respectively, bleachable yellow, magenta, and cyan-colored dyes. After an imagewise exposure, these'elements can be developed in a black and white silver halide developer solution to formlow-contrast silver images in the exposed layers. Subsequent to such development, the element is subjected to one or more acidic bleaching solutions comprising, as an active component, an agent commonly referred to as a bleach catalyst. This bleach catalyst oxidizes the metallic silver formed during developmentand in so doing is itself reduced. The reduced catalyst then acts at the points where silver was present to reduce the colored, bleachable dye in each layer to a colorless product, while the catalyst is simultaneously oxidized to its original state. Residual s'ilver salt is then removed by fixing and washing. A positive, colored dye image is thereby produced which is photographically the inverse of the initial silver image.

In the acidic bleaching processes, dyes tend to migrate when subjected to treatment with the bleaching solution. Since movement can decrease the intimate contact of silver and dye, which separation impedes effective bleaching, the net result is a higher minimum dye density (Dmin) which reduces contrast in the final dye image. Another effect of increased Dmin is decreased speed insofar as the minimum dye density occupies a density range which would otherwise be available for producing the developed dye image.

As is described above, a multilayer photographic element, wherein each photosensitive layer exhibits photosensitivity toward only a narrow spectral range, can be developed by dye bleach techniques to produce a positive, polychromatic dye image of an original. However, the above-described migrating characteristic of the dye not only produces the previously discussed effects, but also effects a deterioration in the fidelity with which the hues of the polychromatic dye image reproduce the hues of the original, since the dyes exhibit the tendency to move into and thereby contaminate the adjacent, contiguous dye-containing layers.

Another difficulty encountered in multicolor dye bleach systems is the difficulty with reproducing hue intensity. Sensitizing dyes amenable to dye bleach systems typically have extended absorption spectra which render it exceedingly difficult to prepare a multilayer photographic element wherein each dye layer is photosensitive to only a comparatively narrow band of the visible spectrum. If the desired narrow spectral absorption in each dye layer is not obtained, the color balance is distorted, selected hues being either overaccentuated or underaccentuated, depending upon the relative amount of activating light impinging on each such layer.

Highly basic bleaching solutions for dye bleach systems experience difficulties similar to those outlined above for the acidic solutions. Additionally, the bleachable dyes tend to be excessively soluble in the bleaching solution which results in a lowering of the maximum dye density (Dmax), and hence an additional decrease in contrast.

Accordingly, given the above-mentioned difficulties associated with dye bleach systems, it is known to employ a mordanting material which functions to retain the dye as coated and avoid the problem areas associated with dye migration either in one layer or between contiguous layers. Known mordanting materials, however, have met with varying partial success in retaining dyes in dye bleach systems and narrowing the absorption spectra of such dyes. Moreover many of the known mordants cannot withstand the degrading effects of the alkaline and acidic bleaching solutions.

Accordingly, it is an object of this invention to provide new cationic mordants in dye-bleaching systems.

It is another object of this invention to provide, for dye bleach processing, novel photographic elements in which the bleachable dye exhibits a decreased tendency to migrate during development.

Still another object of the present invention is to provide, for dye bleach processing, new photographic elements in which bleachable dye is sensitive over a decreased spectral range.

Yet another object of this invention is to provide, for dye bleach processing, novel photographic elements which exhibit a higher contrast in the developed dye image.

Still another object of the instant invention is to provide, for acidic dye bleach processing, new photographic elements which possess a decreased minimum dye density in the developed dye image.

Still another object of the present invention is to provide, for alkaline dye bleach processing, new photographic elements which exhibit an increased maximum dye density in the developed dye image.

Yet an additional object of this invention is to provide a new photographic process for producing positive, colored-dye images by acidic dye bleach means.

Still another object of the instant invention is to provide a novel photographic process for producing positive, colored dye images by alkaline dye bleach means.

These and other objects of the present invention will become apparent from a consideration of the following specification and claims.

The objects of the present invention are accomplished with photographic elements designed to produce positive, coloreddye images by dye bleach techniques, which elements comprise a support having coated thereon at least one light-sensitive layer comprising a silver halide emulsion, an anionic bleachable azo dye and a poly(styrene-maleimide) cationic mordant for such dye.

Typical poly(styrene-maleimide) cationic mordants useful in the present invention include quaternary ammonium salts derived from styrene, the imide of maleic anhydride and an acid, and which cationic polymeric mordants correspond to the general formula:

wherein R and R, are each a hydrogen atom or a lower alkyl radical having 1 to 8 carbon atoms such as methyl, ethyl, npropyl, secbutyl, tert-butyl, n-pentyl, n-heptyl, n-octyl, etc.; R is a phenyl radical and includes substituted phenyl radicals; R R and R are each a lower alkyl radical having one to eight carbon atoms such as methyl, ethyl, n-propyl, sec-butyl, tertbutyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, etc.;, R is a lower alkylene radical having two to eight carbon atoms such as ethylene, trimethylene, tetramethylene, pentamethylene, etc.; Z is an integer larger than 10; Z, is an integer ranging from at least &2 to Z; Z is an integer ranging from at least #2 to Z; and R is an anion, including anionic acyloxy radicals such as benzoyloxy, pentanoyloxy, p-toluene sulfonyloxy, etc.

Particular examples of the cationic mordants described herein are copoly[styrene N-(ytrimethyl ammonium propyl)- maleimide p-toluene sulfonate], copoly[styrene N-(B-diethylmethylammonium ethyl)-maleimide p-toluene sulfonate], copoly[styrene N-B-(dimethylethylammonium ethyl)-maleimide p-toluene sulfonate], copoly[styrene N-(A-trimethylammonium-n-butyl)-maleimide p-toluene sulfonate], copoly[styrene N-(A-dipentylpropylammonium-n-hexyl )maleimide p-toluene sulfonate].

The preparation of suitable mordants is described generally in Minsk et al., US. Pat. No. 3,048,487. Minsk et al. describe the preparation of the imide of styrene and maleic anhydride as substituted with a disubstituted amine linked to the nitrogen of the imide by a lower alkylene group, and one can prepare the quaternary ammonium salt of the above-described copolymeric imide and an acid by, for example, first treating the amino substituted imide with an alkyl halide such as methyl iodide, ethyl chloride, n-propyl iodide, n-butyl iodide, etc., and then displacing the imide from the halogen salt by treatment with a suitable acyl derivative such as sodium ptoluene sulfonate.

The anionic, bleachable azo dyes which are typically used in dye bleach systems in conjunction with the above-described cationic mordants of this invention are well-known azo dyes such as monoazo, diazo, triazo, tetraazo, etc., dyes which are rendered colorless in the presence of silver and a bleaching solution as in the two previously mentioned types of dye bleach systems. Particular examples of bleachable, anionic azo dyes include a yellow colored diazo dye having the formu- S OaNa CH3 ll K N=N NH -o l S O3N8 2 and a cyan colored tctraazo dye having the formula:

C 2H5 I N=:N- N=N S i l- Nu NH: N=N

i S OaNa N Other typical azo dyes are also described herein. Additional azo dyes are well known in the art.

Single-color photographic elements which are advantageously processed (after an imagewise exposure) by dye bleach means to provide positive, colored dye images are prepared by coating a support with a light-sensitive layer, which light-sensitive layer typically includes a silver halide emulsion, an anionic bleachable azo dye of the type previously described and a cationic mordant of the present invention. Any of the usual photographic silver halide emulsions can be used including silver chloride, silver bromide, silver bromoiodide, etc. Gelatin or other hydrophilic colloids as a binder for the silver halide, and coating aids such as saponin, as well as other conventional emulsion addenda such as spectral sensitizers, chemical sensitizers, antifoggants, etc., are also generally included in the coated light-sensitive layer.

The choice of a support material can be widely varied. Paper, including polyethylene-coated paper, polypropylenecoated paper and pigment-coated paper such as baryta and titanium dioxide-coated paper is advantageously employed as a support material. Polymeric materials are typically used supports and include such conventional photographic film supports as cellulose acetate, cellulose nitrate, cellulose acetate butyrate, cellulose butyrate, polystyrene, poly(ethylene terephthalate) and other polymeric materials which are well known in the an.

The method by which the light-sensitive layer is coated upon the support material can be any known to those skilled in the art. Doctor blade coating, dipping, hopper coating and hand swabbing are examples of typical coating means. The components of the light-sensitive layer can be coated together. Alternatively, all of the components except the dye can be coated, and after the coating is dried, it can then be immersed in a bleachable, anionic azo dye solution until the desired dye density is obtained.

In the coated, light-sensitive layer, the weight ratio of mor dant to dye can be widely varied, with a range of from about 10 percent to about percent being useful. Regarding the amount of silver present in a layer (as it would be developed from silver halide emulsion), it need only be an amount suffcient to catalyze or effect the reductive dye bleaching.

Multicolor elements are prepared by coating a support, such as those described above, with separate, essentially contiguous silver halide layers differentially sensitized to blue, green and red radiation and having in association therewith, respectively, yellow, magenta and cyan colored bleachable azo dyes. In the case ofa multicolor element, the silver halide emulsion and bleachable azo dye associated with each layer are admixed and coated to form the separate light-sensitive layers.

A photographic element of the invention can be imagewise exposed through an original pattern to a source of visible radiation, producing at least one metallic silver latent image which is developed and fixed by conventional black and white means. The developed metallic silver image or images then function as either reducing agents or catalysts in the subsequent bleaching operation, depending upon whether, as noted above, the bleaching is carried out in an acidic or alkaline atmosphere.

Bleaching is effected by contacting the photographic element, which has been exposed and developed, with an acidic or an alkaline bleaching solution for a period of time sufficient to effect the chemical reduction of the colored azo dyes to colorless forms. Typical alkaline bleaching solutions are reducing agents such as alkali metal hydroxides which have been activated by the addition of a metal salt, stannous salts for example. A preferred alkaline bleaching agent is sodium stannite, a combination of sodium hydroxide and stannous chloride. Typically, its concentration is such that the pH is advantageously in excess of about 11. A generally used acidic bleaching composition is acidic thiourea and a typical formulation is as follows:

Concentrated HCI I00 ml. Thiourea g. Z-hydroxy-J-aminophenazine 0.15 g. Water to make I liter After bleaching, residual silver can be removed by treatment with ferricyanide and a conventional fixing agent such as sodium thiosulfate. The result is a high-quality monoor multicolored dye image which is a positive reproduction of the original. Such image, if present on an opaque support, can be viewed in conventional fashion via reflected light. If the support is a transparent material, cellulose acetate or poly(ethylene terephthalate) for example, the final dye image is amenable to viewing via transmitted light such as by projection.

Such photographic elements as are described above, utilizing the cationic mordants of the subject invention, are processed by conventional dye bleach techniques to produce improved dye images. Under acidic processing conditions, the dyes exhibit less tendency to migrate, producing more effec tive bleaching which results in a lower Dmin and increased speed and contrast. When alkaline bleaching is employed, the dyes are less soluble in the bleaching solution and a higher Dmax and increased contrast result. in multicolor elements wherein the poly(styrene-maleimide) cationic mordants are employed, in addition to the above noted advantageous results, dyes show a decreased migration between layers and also a more precise spectral absorption. The mechanism whereby these advantageous results are obtained is the formation of a salt of the dye and the mordant, which reduces the tendency of the dye to physically or chemically interact with the bleaching solution except in the presence of a silver image. Regarding the decreased spectral absorption, it isspeculated that the subject mordant tends to preferentially retain the dye in one of a plurality of possible tautomers, thereby producing a narrower spectral absorption more closely matching that of one tautomcr.

The invention is further illustrated by the following examples which include preferred embodiments thereof.

EXAMPLE 1 A melt (melt A) is prepared by mixing 40 ml. distilled water, 20 ml. of 5 percent by weight of aqueous copoly[styrene-N-('y-trimethylammoniumpropyl)-maleimide p-toluene sulfonate] as a mordant, 20 ml. of a percent gelatin-silver bromoiodide emulsion and 2 ml. of percent saponin, with sufficient distilled water added to bring the total melt weight up to 94 g. The melt is then hopper-coated (coating A) on a white pigmented titanium dioxide paper support to provide a coverage of 100 mg./ft. of mordant, 200 mgJft. of gelatin and 100 mg./ft. of silver. A second melt (melt B) is prepared in the same manner as melt A, except that copoly -[styrene-N-(fl-diethylmethylammonium) ethyl maleimide ptoluene sulfonate] is substituted in like quantity as the mordant.lt is coated (coating B) in the same manner as coating A. A third melt (melt C) is prepared in the same manner as melt A, except that ml. of a washed gelatin dispersion of poly-amethyl-allyl-N-guanidyl ketimine glycolate (a known dye bleach mordant described in U.S. Pat. No. 2,882,156) is substituted in like quantity as the mordant. It is coated (coating C) in the same manner as coating A. A portion of each of the three dried coatings is immersed in a 1 percent solution of an anionic, magenta colored azo dye having the formula:

Elon 3 g. Sodium sulfite, desiccated 45 g. Hydroquinone 12 g. Sodium carbonate. monohydrated 80 Potassium bromide 2 5. Water to makc 1 liter to which is added 2 g. of potassium thiocyanide and 0.05 g. of S-methylbenzotriazole per liter of developing solution. After conventional fixing in aqueous potassium thiosulfate to remove undeveloped silver halide, the portions of coatings A and B are then immersed for seconds in a bleaching solution of 10 percent aqueous sodium hydroxide to which is added 5 g. per liter of stannous chloride. The portion of coating C is immersed in a like bleaching solution, but for a period of only 30 seconds. Coatings A and B exhibit significantly less tendency to solubilize in the alkaline bleaching solution than does coating C, and as such, A and B retain a much higher dye density after removal from the processing solution than does coating C, which is representative of currently known mordants for dye bleach systems.

EXAMPLE 11 Another portion of each of coatings A, B and C as described in Example I is immersed in a cyan-colored azo dye having the formula:

higher maximum dye density after such treatment. Moreover,

when a portion of coating B and a portion of coating C are immersed in 20 percent aqueous sodium hydroxide to which is added 5 g./l. stannous chloride, the portion of coating B exhibits greater dye density after 2 minutes of such treatment than does the part of coating C after 30 seconds.

EXAMPLE Ill A melt (melt D) comprising 0.3 g. of a cyan-colored dye having the formula:

E Q- U S OaNa dissolved in 19.5 ml. of distilled water, 45 g. of a washed dispersion of poly-a-methylallyl-N-guanidyl ketimine glycolate mordant in gelatin, 6.5 ml. of 10 percent gelatin, 1.5 ml. of 7.5 percent saponin, 0.5 ml. of 40'percent formalin, and 10 ml. of a gelatino silver bromoiodide emulsion is coated (coating D) on titanium dioxide pigmented poly (ethylene terephthalate) support to provide 30 mg./ft. of cyan dye, 300 mg./ft. of gelatin, about mg./ft. of silver and mg./ft. of mordant. The coating is then dried. Another melt (melt E) is prepared in like fashion, except that a 5 percent aqueous solution of copolylstyrenel-N-('y-trimethylammonium) propylmaleimide p-toluene sulfonate] is substituted as the mordant. It is coated (coating E) and dried in the manner of coating D. A portion of each coating is exposed through a standard 0.15 log E step wedge and is then developed in a black and white developer solution having the formula:

Elon 3 g. Sodium sulfite. desiccated 45 g. Hydroquinone 12 g. Sodium carbonate, monohydrated 80 3. Potassium bromide 2 g. Water to make 1 liter to which is added 2 g. of potassium thiocyanide and 0.05 g. of S-methylbenzotriazole per liter of developer solution. After conventional fixing in aqueous potassium thiosulfate to remove undeveloped silver halide, dye-bleaching of each coating is accomplished by a 30-second immersion in a solution having the formula:

Thiourea I25 3. Concentrated HCI 100 ml. 2-hydroxy-3-aminophcnazinc 0.15 g. Distilled water to I liter Dmax at m= Dmin Speed Contrast Coating D 0.90 at 646 yellow control low (Control) stain contrast Coating E 0.97 at 648 less yellow +.2 log E higher stain contrast Moreover, the portion of coating E exhibits significantly less green absorption than does the portion of coating D, thus illustrating the increased suitability of the subject mordants for use in polychromatic dye bleach systems.

EXAMPLE IV A titanium dioxide pigmented poly(ethylene terephthalate) support material is coated with a first layer comprising 203 mg./ft. of gelatin and 100 mg./ft. of silver (as components of gelatino silver bromoiodide emulsion), 26 mg./ft. of an anionic cyan colored azo dye having a formula as described in Example 111 to spectrally sensitize the emulsion to record red light and 63 mg./ft. of copoly-[styrene-N-(y -trimethylammonium) propylmaleimide p-toluene sulfonate] as the mordant. A second layer is coated contiguous to the first layer, the second layer comprising 206 mg./ft. of gelatin and 100 mg./ft. of silver (as components of a gelatino silver bromoiodide emulsion), 26 mg./ft. of an anionic magenta colored azo dye having a formula as described in Example I to spectrally sensitize the emulsion to record green light and 66 mg./ft. of the cationic mordant previously described in this example. A third layer is then coated over and contiguous to the second layer, the third layer comprising 310 mg./ft. of gelatin and 100 mg./ft. of silver (as components of a gelatino silver bromoiodide emulsion), 35 mg./ft. of an anionic, yellow-colored azo dye having the formula:

S OaNa mg./ft. of the mordant used in the first two layers. The composite, three-color photographic element so coated is then exposed to a multicolor positive transparency. After exposure, the element is then developed, fixed and bleached as described in Example 111. After such processing the developed coating exhibits a three-color positive image.

An illustrative preparation of a mordant of the type used in this invention is as follows.

Preparation of copoly[styrene-N-('y -trimethylammoniumpropyl)-maleimide p-toluene sulfonate]: A solution of 20.2 g. (0.1 mole) of styrene-maleic anhydride interpolymer in 200 ml. of dimethylformamide is added slowly to a solution of 14 g. (0.14 mole) of y -dimethylaminopropylamine in 200 ml. of dimethylformamide to form a white, gummy precipitate. When the reaction is carried out on a steam pot, the precipitate slowly dissolves. However, cooling the mixture causes precipitation to occur. The solution is slowly distilled with stirring until 100 ml. of distillate is collected. The still pot temperature slowly rises from to C. during this procedure. On cooling there is no precipitate. The product precipitates as a friable powder on pouring into water. It is washed with water, filtered and vacuum dried. Analysis, C, 70.5, 70.7; H, 7.7, 8.0; N, 9.4, 9.4. One hundred ninety-five grams of the polymer thus prepared is dissolved in 2 liters of dimethylformamide with mechanical stirring at room temperature. Six hundred fifty grams (3.45 mole) of methyl ptoluenesulfonate is stirred in and the solution allowed to stand at room temperature for 4 days. The polymer is precipitated in 16 liters of acetone. The white granular precipitate is washed three times in 3-liter portions of acetone. The precipitate is filtered, pressed dry and redissolved in 1 liter of methanol. The methanol dope is treated with 10 g. of decolorizing carbon at 60 C. The carbon is filtered out on a Filtrol pad, with suction. The filtrate is precipitated in 15 liters of acetone. The precipitate is washed three times with 4-liter portions of acetone, filtered, and pressed dry under a rubber dam, and dried at reduced pressure for 3 days at room temperature. Yield, g. Anal. Calcd.: N, 5.9; S, 6.7. Found: N, 5.5; S, 6.5

The invention has been described above in considerable detail, with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

We claim:

NH2 S OaNa 0 N=N our- S OaNa B osNti NH:

S OsNa 3. A photographic element as described in claim 1 wherein 6. A photographic element as described in claim 5 wherein, the anionic, bleachable azo dye has the formula: in the cationic mordant,

omoomr OH 0033 OH H:) (0H OH\' I L (L y J 4 N sOnNfl -S OQNEL CH3 l e (GHQ-3 R 0H 17TH: 1 6) l N=N- V. .9. l. V a each of R and R is a hydrogen atom, each of R R and R is S0;Na- S O Na a methyl radical and R is a trimethylene radical.

V y 7. A photographic element as described in claim 5 wherein in the cationic mordant, 4. A photographic element as described in claim 1 wherein the anionic, bleachable azo dye has the formula:

SOaNa NH 8. A photographic element as described in claim I wherein the support is poly(ethylene terephthalate) coated with a white pigment.

9. A photographic element as described in claim 1 wherein the support is paper coated with a white pigment. r,, e. 10. A silver dye bleach process for treating an imagewiseexposed photographic element to produce photographic 5. A photographic element as described in claim 1 wherein i id photographic element comprising a support haythe cationic m r anl h h f m l ing coated thereon a light-sensitive layer comprising a silver halide emulsion, an anionic, bleachable azo dye and a R R1 poly(styrene-maleimide cationic mordant for said dye, which i process comprises sequentially contacting said photographic each of R and R is a hydrogen atom, each of R and R is an ethyl radical, R is a methyl radical and R is a methylene radical.

7 1 element with L (L a. a black and white photographic developer composition 2 for a period of time sufficient to produce a silver image in the areas of exposure,

I b. a photographic fixing composition for a period of time sufficient to remove the unexposed silver halide and c. a bleaching solution for a period of time sufficient to render the azo dyestuff colorless in the areas bearing a 1 w-BJQ photographic silver image. wherein; 11. A process as described in claim 10 wherein the a. R and R are each selected from the group consisting of a bleachmg solutlo has the formula:

hydrogen atom and a lower alkyl radical, b R2 i a h l di l Concentrated HCI 100 ml.

- Thiourea I25 gr 0. I3 R and R are each lower alkyl radicals, ydmyavaminophenazine 15 8. R IS a lower alkylene radtcal, Water to make 1 liter e. R is an anion, f. 2 is an integer larger than l0, 12. A process as described in claim 10 wherein the g. Z is an integer ranging from at least lzZ to Z, and bleaching solution comprises a stannous salt and has a pH of at h. Z is an integer ranging from at least /2Z to Z. least about 1 l 32 3 IUNITED- "BATEN'I" OFFICE CERTIFICATE KCOBRECTIGN Patent No. -2 If I v I Dated February r Inve t-0 dafal f l r'Williams}Jr; mam-111m Knechel "theabove-identified patent and chat: s'aid Letters Patent arejherepy corrected as shown below:

I Column 8, a line 52, :afterlthe word 'imageWinsert v "and a poly(styrene -maleimide) cationic mordant for said dyer 061mm 9, lines 3 to 7, n the" lower left-hand portion of the formula the radical "SO N a" should-be --SO l Ta--.

' Column 10, ."lines 3 to '12, the entire structural formula should be deleted. m

Column 10, lines l7 to"2L|., the entire structural formula should be deleted.

Signed and sealed this 2nd day of January 1973 (SEAL) Attest:

EDWARD M.FLETCHER JR I Attegti Off ev ROBERT GOTTSCHALK Commissioner of Patents 

2. A photographic element as described in claim 1 wherein the anionic, bleachable azo dye has the formula:
 3. A photographic element as described in claim 1 wherein the anionic, bleachable azo dye has the formula:
 4. A photographic element as described in claim 1 wherein the anionic, bleachable azo dye has the formula:
 5. A photographic element as described in claim 1 wherein the cationic mordant has the formula:
 6. A photographic element as described in claim 5 wherein, in the cationic mordant,
 7. A photographic element as described in claim 5 wherein, in the cationic mordant,
 8. A photographic element as described in claim 1 wherein the support is poly(ethylene terephthalate) coated with a white pigment.
 9. A photographic element as described in claim 1 wherein the support is paper coated with a white pigment.
 10. A silver dye bleach process for treating an imagewise-exposed photographic element to produce photographic images, said photographic element comprising a support having coated thereon a light-sensitive layer comprising a silver halide emulsion, an anionic, bleachable azo dye and a poly(styrene-maleimide cationic mordant for said dye, which process comprises sequentially contacting said photographic element with a. a black and white photographic developer composition for a period of time sufficient to produce a silver image in the areas of exposure, b. a photographic fixing composition for a period of time sufficient to remove the unexposed silver halide, and c. a bleaching solution for a period of time sufficient to render the azo dyestuff colorless in the areas bearing a photographic silver image.
 11. A process as described in claim 10 wherein the bleaching solution has the formula: Concentrated HCl 100 ml. Thiourea 125 g. 2-hydroxy-3-aminophenazine 0.15 g. Water to make 1 liter
 12. A process as described in claim 10 wherein the bleaching solution comprises a stannous salt and has a pH of at least about
 11. 